Over the past decade there has been a trend towards the use of lower temperatures in domestic fabric laundering, arising from the increased incidence of coloured fabrics, the greater use of synthetic fibres in fabric manufacture and the need to conserve energy. This trend has in turn led to the development of concentrated liquid detergent formulations for laundry use, because this product form is better adapted to low temperature usage. At the present time, granular detergent compositions are not totally satisfactory for use under cold water washing conditions because of weaknesses in the areas of dissolving speed, product insolubility, and consequently cleaning efficiency.
The formulation flexibility for liquid detergent compositions is limited, particularly in respect to inorganic materials such as silicates. The latter compound is essential, in solid detergents, to ensure adequate compatibility of the laundry liquor with the washing machine, in particular with enamel-coated surfaces. To date, no suitable silicate-substitutes for convenient use in liquid detergent compositions have been developed and an unfulfilled need exists for such materials. A satisfactory substitute should exhibit its functionality not solely at relatively high alkaline pH such as needed by silicates, but over a broad range of conditions extending from e.g. neutral to alkaline (pH 6-12) conditions such as are found in liquid detergents. The silicate-substitute should furthermore be compatible with the physical state of the matrix, it must allow the preparation of homogeneous compositions and it should also be compatible with individual ingredients and not be subject to deactivation/precipitation phenomena.
Silanes and amino-silanes are widely used in the chemical industry, mostly as coupling agents between inorganic and organic surfaces. These compounds have also found application for metal-surface protection. The protective treatment is applied from an aqueous medium, possibly from solvent systems containing lower alcohols and water, depending upon the characteristics of the silanes. Representative of this stage of the art are: U.S. Pat. No. 3,085,908, Morehouse et al., U.S. Pat. No. 3,175,921, Hedlund, and French Pat. No. 1,207,724, Morehouse et al.
Quaternized amino-silanes are known, from U.S. Pat. No. 4,005,118, Heckert et al. and U.S. Pat. No. 4,005,025, Kinstedt, to be suitable for conferring soil release properties to metallic and vitreous surfaces upon application from a wash or rinse-solution. The like quaternized amino-silanes, upon incorporation in aqueous detergents, are subject to deactivation, possibly following polymerization during storage.
It is also generally known that silane metal-surface treatment is usually carried out under slightly acidic conditions (pH 3-5) in order to prevent polymerization of the silane monomers in the aqueous medium, which polymerization is known to decrease the effectiveness of the surface treatment.
The preparation of a broad class of gamma-amino-propylalkoxysilanes is known from German Application DOS No. 17 93 280.
Silanes, inclusive of amino-silanes, have been used in industrial fiber treatment technology, mostly in combination with polysiloxanes. This art is represented by German Patent Applications: DOS No. 27 26 108; DOS No. 14 69 324; DAS No. 23 35 751; and U.S. Pat. No. 4,152,273, Weiland.
Such known industrial fiber/substrate treatments quantitatively aim at chemically attaching, to the substrate, an organic polymer with a view to impart permanently modified fiber properties such as water-repellency, shrink-proofing, bactericidal properties, and so on. Silanes are used in a coupling/adhesion agent functionality, i.e., the silane is non-releasably affixed to the substrate. For example, a process for giving permanent shrink resistent properties to woollens as known from Belgian Pat. No. 802.311, Dow Corning, uses a mixture of organopolysiloxanes and silanes.
Treatment compositions for synthetic fibers containing amino-silanes and epoxysiloxanes are known from German Patent Application DAS No. 25 05 742, Tenijin Ltd. The treated fibers have enhanced compression-elasticity, smoothness, flexibility, softeness and good usage characteristics. The silane acts as a coupling agent for depositing the active ingredient, i.e., the silicones.
French Patent Application No. 2.299.447, Rhone-Poulenc, describes flexible water-insoluble substrates impregnated with a detergent suds regulant, preferably an orango-polysiloxane, in a level such that the regulant represents from 1% to 200% of the substrate.
None of the prior art references addresses the problems inherent in the development of laundry additives with a view of conferring, better machine compatibility, especially in relation to enamel-coated surfaces. This compatibility results from the use of the laundry additive itself. In addition, the surface protection lasts throughout the subsequent laundry treatments carried out in the machine.
It has now been found that specific amino-silanes can be used as silicate-substitutes in laundry liquors and in the concurrently filed application Ser. No. 421,187, now U.S. Pat. No. 4,416,793 entitled "Liquid detergent compositions containing amino-silanes", amino-silanes are disclosed which have acceptable stability and performance characteristics in such compositions.
It is an object of the present invention to provide a solid laundry additive product comprising an amino-silane, effective in preventing or inhibiting vitreous enamel corrosion in aqueous detergent media, in combination with an inert carrier.